Lapping machine



May 12, 1925. 1,537,182

H. 1.. NICHOLSON LAPPI NG MACHINE Filed Feb. 15, 1924 2 Sheets-Sheet 1 INVENTOR May 12, 1925.

1,537,182 H. L. NICHOLSON LAPPING MACHINE Filed Feb. 15, 1924 2 Sheets-Sheet 2 nnnmmmmmuumlI INVENTOR angles to thatof Fig. 1.

platestaken by themselves with plate carrying piston ringsto be lapped in Patented May 12, 1925;

HARRY 1,. nrcnorsoiv, or WILMERDING, rnnnsriivama.

LAPPING azacnrnn.

Application filed February 15, .1924. SeriaiNo. 692,986.

To all whom it may concern:

Be it known that I, HARRY a citizen of the United States, and-a resident of Wilmerding, in the county of Allegheny and State of Pennsylvania, have made a new and useful invention in Improvements in a Lapping Machine, of Which the following is a specification.

The invention relates to lapping mas chines. It is designed particularly for lapping piston rings, in order to make them'of a definite thickness and to bring their opposing surfaces into exact parallelism, but it will be understood that the invention is not'limit'ed to this particular use, andthat the machine may be usedto" advantage for lapping other articles. The invention has for its primary objects; the provision of a lapping machine having improved means for securing a uniform distributionof wear over the abrading surfaces; the provision of improved means for regulating the move ments of th'e'carrier plate in which the mem bers to be lapped are carried; the provision of an improved arrangementin which the wear of the parts is reduced to a minimum and the parts subject to wear are readily replaceable; the provision of an improved arrangement in which the members-to be lapped may be rapidly and conveniently positioned in the machine or removed and replacedby others; and in general, the provision of a machine having a very simple arrangement of parts with which a large amount ofwork can be handled with great accuracy and at a minimum cost.- One embodiment of the invention is illustrated in the accompanying drawings, wherein:

Figure 1 is a vertical section through the machine. Fig. 2 is a plan view with the top lapping plate removed to show theicarrier plate with the members to be lapped (piston rings) in position therein- Fig. 3 is an enlarged sectional view. through the lapping position therein, the showing of certain of the parts and the thickness of the plates and abrasive facings being (for clearness of illustration) out of actual proportion. And

Fig. 4 is an enlarged section taken through the crank construction in. a plane at right Briefl stated, the machine, in its preferred orm, comprises a pair of opposing lapping plates faced with annular members,

the members or pieces to such plate to maintain itself the carrier.

shaft 6. v

of abrasive fabric, such. asemery cloth, L. NICHOLSON,

with an interposed carrier plate, in which ferred to hereafter for definiteness as piston rings), are. loosely mounted, together with means for giving such plate an eccentric circular motion, so that the piston rings are carried around the axis of rotation of the carrier and alsomoved transversely of .the abrading surfaces, to distribute the wear thereover, the piston rings being also free to rotate about-their own axes in their perforations in the carrier plate. Provision is made whereby the extent of the eccentric movement of the carrier plate may be adjusted to give the most uniform distribution of wear over the abrading surfaces, and a uniform and exact reduction of the surfaces of the piston rings. Provision is also made forhinging the upper lapping plate, so that it may be swung out of the way in positioning the piston rings in, and removing them from, the carrier plate, while at the same time permitting in parallel relation withthe lower lapping plate during the lapping operation. The driveof the carrier plate is from beneath, so that both lapping plates and the carrier plate may be removed without any loss of time in re moving and replacing the piston rings and in replacing the abrading fabrics. W'hile is is simpler.to secure the desired relative movements between the carrier plate and lapping plates by giving the carrier plate the necessary movements, it is possible to secure a similar lapping effect, by revers-' 3, having atits center the sleeve 4, provided with a suitable bushing 5, carrying the crank shaft 6. The upper end of thisshaft is supported in another bushing 7 carried by the base casting. Theshaft 6 is. driven from the shaft 8 by means of the pinion 9 the gear 10, pinned to the meshing with The-upper end 11 ofthe shaft G eXtends laterally and is providedwith a dove tail slot be lapped (re- 12 (Fig. 4:) in which is mounted the nut- 13 carrying the crank pin'l l, such pinhav ing a head formed so as to be readily engaged by a wrench. The pin carries a hardened roller 16 for taking the wear and reducing the friction at this point, and is held in adjusted position in the slot 12, by screwing it down against the bottom wall of such slot (Fig. 4:).

The lapping plates employed, are preferably in the form of a pair of castings 17 and 1S, the lower one of which is supported upon the annular rib 19 integral with the base casting 2. To hold the plates against rotation, and guidethem vertically, the base casting isprovided with a pair of rigid upstanding pins 20, 20 2) which fit loosely in suitable perforations carried by laterally extending lugs 21, :21, integral with each plate. The base casting 2 and the upper plate 18, are also provided with hinge lugs 22 and 23 through which extends a pintle 2 f, so that the top plate may be readiiy swung up'out of the way to give access to the carrier plate, the lug 25 on the base casting acting as a stop when the plate is swung ,to open position. As indicated at 2%, Fig. 1, a small amount of lost motion is provided in one of the hinge lugs for the pintle, so that during the lapping operation, the upper plate is free to move vertically in a right line, instead of moving on an are around the pintle, as would be the case, if a close fit for the pintle were employed. Any tendency to lap the piston rings so that their opposing faces are not parallel, is thus avoided, while retaining the advantage in manipulation of the upper plate incident to having it attached for swinging movement instead of having it entirely detached.

In order to provide abrading surfaces for the lapping plates, the annular facing members 26 and 27 are preferably employed, such members being concentric with the center line of the plates, and preferably consisting of a fabric coated with abrasive, such as emery cloth. although any other desired abrading surfaces might be employed. These members are cemented to the plates, and may be readily removed and replaced when worn, the mounting of the plates, as heretofore described, serving to give ready access to-their faces for this purpose.

7 Between the lapping plates is the carrier plate 28, preferably ofthin sheet steel havinga central perforation, and a plurality of perforations-29 for the reception of the piston rings :30 to be lapped, such perforations preferably having a diameter about one eighth, of an inch greater than the diameter of the piston rings to be lapped, so that the rings areefree to turn about their own axes, "Mounted in the central perforation is the hardened wear ring 31 secured in posit on by any suitable means, such as by riveting. The inner dameter of this ring is considerably greater than the diameter of the roller 16, as indicated in the drawin s, thus increasing the wearing surface of tie bushing and increasing its life, and giving the carrier plate a wider latitude of movement for distributing the wear over the abrading members 26 and 27. As indicated in Fig. 3, this feature in connection with the throw of the crank is such, that when in one extreme of movement, the rings 30 extend out past the outer periphery of the abrading members 26 and 27 right of Fig. 3) ,at which time, the rings on the opposite side of the carrier, extend inside the inner periphery of such members, so that the wear on the members is distributed over their entire surface. The extent of this lateral movement of the carrier plate and the amount which the rings are carried past the peripheries of the abrading members may be regulated by adjusting the throw of the crank to meet conditions and secure the best results. This feature of adjustment, also comes into play when a different carrier plate is placed upon the machine with perforations of a different diameter for use in lapping rings of a different diameter. The construction of the machine facilitates changes of this kind, as well as renewals of the abrading fabrics, and the removal, and replacement of the piston rings, as all that is necessary is to swing the upper lapping plate upward about its pivot, and lift off the carrier plate. i

In operation, the plate 1 is first swung upward and the perforations in .the carrier plate 28 filled with the rings to be lapped, after which the top plate is lowered and the driving mechanism for the crank shaft thrown into operation. The rotation of the crank rotates the carrier plate bodily about the EDTlS of theshaft. This gives the piston rings in the carrier a movement circumferential of the annular abrading members 26 and 27, which movement is made eccentric, so as to carry them laterally from the inner periphery of the members to the .outer peripheries by reason of the action of the crank and the lost motion of the crank pin roller 16 in the wear bushing 81. By trial and inspection, the throw of the crank is adjusted so as to secure thebest results in lapping and the most uniform wear oft-he abrasive facings for a certain s'ize of piston rings in a given carrier plate, after. which these conditions are maintained for succeeding operations. The reduction in thickness of the piston rings is gauged'by the time consumed, so that after itfis determined'iby trial in one instance, 'hpw long is required to reduce unfinished piston rings of a certain dimension to a given definitethickness and with parallel surfaces, the operation may be accurately repeated over andover again at a very rapid rate to face a large number of rings, no measurements or observation being required except to maintain the period of lapping constant for the successive sets of rings, using care, of course, to replace the abrading members from time to time, as they. become wor Aside from the abrasive facings, the wear upon the parts of the machine and the requirement for replacements is slight, the use of the roller 16 on the crank pin, in conjunction with the lost motion in the wear ring 31,-reducing the wear at the point, where wear is most liable to occur, to a minimum.

What I claim is: r

1. In combination in a lapping machine,

a pair of opposing lapping plates having annular abrading surfaces, a carrier plate between such plates provided with perforations for the members to be lapped, and having a circular central perforation, a crank having its axis of rotation concentrio with that of said annular abrading surfaces and having its free end of substantially less diameter than that of said circular perforation so that it fits loosely in said central perforation in the carrier plate, and means for driving the crank.

2. In combination in a lapping machine, a pair of opposing lapping plates having annular abrading surfaces, a carrier plate between such plates comprising a, sheet metal plate having a central perforation and a series of other perforations surrounding said central perforation for the reception of the members to be lapped, an annular wear ring secured in said central perforation, and a driven crank having its axis of rotation concentric with the annular abrading surfaces and having its free end provided with a roller having a lost motion fit in said wear ring. V r

3. In combination in a lapping machine, a supporting frame, an annular lapping plate mounted thereon, a carrier plate provided with perforations for the members to a supporting frame, an annular lapping plate'mounted thereon, a carrier plate pro- -Y1Cl8d with perforations for the members to 'be lapped carried on the lapping plate, and with a central perforation, a crank shaft for rotating the carrier plate driven from beneath the lapping plate and having a crank end which fits removably in said central perforation, and a secondlappmg plate above the carrier plate hlnged at one side to the frame in such manner-as to per mit movement of said second member at said hinge in a right line parallel to the axis of rotation of the crank means. i

5. In combination 111 a lapplng machine,

lapping means in the form of a pair of op:

posing plates having annular abrading surfaces, carrier means for the articles to be I lapped in the form of a perforated plate mounted between said pair of plates, and

crank'means having a connection with one J of said means and adapted to give it an eccentric circular movement, the said connection being constructed so as to permit of a very substantial amount of lost motion between said crank means and said means.

In testimony whereof, I have hereunto subscribed my name this l2thday of F ebruary, 1924. a e

' HARRY L. NICHOLSON. 

